Ga-68-DOTATOC

Handle Ga 68 DOTATOC Injection with appropriate safety measures to minimize radiation exposure [see Warnings and Precautions (5.1)]. Use waterproof gloves, effective radiation shielding and appropriate safety measures when preparing and handling Ga 68 DOTATOC Injection.

Radiopharmaceuticals should be used by or under the control of physicians who are qualified by specific training and experience in the safe use and handling of radionuclides, and whose experience and training have been approved by the appropriate governmental agency authorized to license the use of radionuclides.

For Ga 68 DOTATOC PET imaging, a whole-body acquisition from the skull vertex to mid-thigh is recommended. Image acquisition can begin at 60 minutes (range 55 to 90 minutes) after the intravenous administration of the Ga 68 DOTATOC Injection. Adapt Ga 68 DOTATOC Injection uptake time and scan duration according to the equipment used, and the patient and tumor characteristics, to obtain the optimal image quality.

Ga 68 DOTATOC binds to somatostatin receptors. Based upon the intensity of the signals, PET images obtained using Ga 68 DOTATOC Injection indicate the presence and density of somatostatin receptors in tissues, .Uptake can also be seen in a variety of non-NET tumors that contain somatostatin receptors or as a normal physiologic variant [see Warnings and Precautions (5.2)]. NET tumors that do not bear somatostatin receptors will not be visualized.

Estimated radiation absorbed doses per injected activity for organs and tissues of adult patients following an intravenous bolus of Ga 68 DOTATOC Injection are shown in Table 1. Estimated radiation effective doses per injected activity for adult and pediatric patients following an intravenous bolus administration of Ga 68 DOTATOC Injection are shown in Table 2.

The effective radiation dose resulting from the administration of 148 MBq (4 mCi) to an adult weighing 75 kg, is about 3.11 mSv. For an administered activity of 148 MBq (4 mCi) the typical radiation dose to the critical organs, which are the urinary bladder wall, the spleen and the kidneys/adrenals, are about 18 mSv, 16 mSv and 12 mSv, respectively. Because the spleen has one of the highest physiological uptakes, higher uptake and radiation dose to other organs or pathologic tissues may occur in patients with splenectomy.

Ga 68 DOTATOC Injection contributes to a patient's overall long-term cumulative radiation exposure. Long-term cumulative radiation exposure is associated with an increased risk of cancer. Ensure safe handling and preparation procedures to protect patients and health care workers from unintentional radiation exposure. Advise patients to hydrate before and after administration and to void frequently after administration [see Dosage and Administration (2.1, 2.3)].

Hypersensitivity reactions following administration of somatostatin receptor imaging agents predominantly consisted of cutaneous reactions such as rash and pruritus. Reactions reversed either spontaneously or with routine symptomatic management. Less frequently hypersensitivity reactions included angioedema or cases with features of anaphylaxis.

The uptake of Ga 68 DOTATOC Injection reflects the level of somatostatin receptor density in NETs, however, uptake can also be seen in a variety of other tumors that also express somatostatin receptors. Increased uptake might also be seen in other non-cancerous pathologic conditions that express somatostatin receptors including thyroid disease or in subacute inflammation, or might occur as a normal physiologic variant (e.g. uncinate process of the pancreas) [see Dosage and Administration (2.5)].

A negative scan after the administration of Ga 68 DOTATOC Injection in patients who do not have a history of NET disease does not rule out disease [see Clinical Studies (14)].

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The safety of Ga-68 DOTATOC injection was evaluated in 334 patients in clinical trials of patients receiving a single dose of Ga-68 DOTATOC injection for imaging known or suspected NET.

The following adverse reactions occurred at a rate of < 2%:
Gastrointestinal Disorders: nausea

The following adverse reactions occurred at a rate of a < 1%
Skin and Subcutaneous Tissue Disorders: pruritus
Vascular Disorders: flushing

The following adverse reactions have been identified during postapproval use of other somatostatin receptor imaging agents. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to the drug.

The safety and efficacy of Ga 68 DOTATOC Injection have been established in pediatric patients with neuroendocrine tumors. Efficacy is based on data from 14 patients in Study A and B demonstrating the ability of Ga 68 DOTATOC to image NETs [see Clinical Studies (14)]. The safety profile of Ga 68 DOTATOC Injection is similar in adult and pediatric patients with somatostatin receptor positive tumors. The recommended Ga 68 DOTATOC injected dose in pediatric patients is weight based [see Dosage and Administration (2.2)].

Clinical studies of Ga 68 DOTATOC did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Ga 68 DOTATOC Injection is a radioactive diagnostic agent for intravenous administration. It contains 3.6 mcg/mL (DOTA-0-Phe1-Tyr3) octreotide, 18.5 MBq/mL to 148 MBq/mL (0.5 mCi to 4 mCi/mL) of Ga 68 DOTATOC at calibration time, and ethanol (10% v/v) in sodium chloride (9 mg/mL) solution (approximately 14 mL volume). Ga 68 DOTATOC Injection is a sterile, pyrogen free, clear, colorless, buffered solution, with a pH between 4 to 8.

Ga 68 DOTATOC, also known as Gallium-68 (DOTA0-Phe1-Tyr3) octreotide, is a cyclic 8 amino acid peptide with a covalently bound chelator (DOTA). The peptide has the amino acid sequence: H-D-Phe-Cys-Tyr-D-Trp-Lys-Thr-Cys-Thr-OH, and contains one disulfide bond. Ga 68 DOTATOC has a molecular weight of 1489.65 g/mol and its chemical structure is shown in Figure 1.

Figure 1: Chemical Structure of Ga 68 DOTATOC

Figure 1

Gallium-68 labeled 2-[4-[2-[[(2R)-1-[[(4R,7S,10S,13R,16S,19R)-10-(4-aminobutyl)-4-[[(2R,3R)-1,3-dihydroxybutan-2-yl]carbamoyl]-7-[(1R)-1-hydroxyethyl]-16-[(4-hydroxyphenyl)methyl]-13-(1H-indol-3-ylmethyl)-6,9,12,15,18-pentaoxo-1,2-dithia-5,8,11,14,17-pentazacycloicos-19-yl]amino]-1-oxo-3-phenylpropan-2-yl]amino]-2-oxoethyl]-7,10-bis(carboxymethyl)-1,4,7,10-tetrazacyclododec-1-yl]acetic acid.

Table 3 and Table 4 display the principal radiation emission data and physical decay of Ga 68.

Gallium-68 (Ga 68) decays with a half-life of 68 minutes to stable Zn 68:

• 89% through positron emission with a mean energy of 836 keV followed by emission of two 511 keV annihilation photons (178%),
• 10% through orbital electron capture (with associated X-ray or Auger emissions), and
• 3% through 13 gamma transitions from 5 excited levels of the daughter Zn 68 nucleus. The most probable prompt gamma emission is a 1088 keV gamma with a 3.2% per decay probability.

Gamma constant: 1.8 × 10^-4 mSv/hr per MBq at 1 meter [0.67 mrem/hr per mCi at 1 meter] Table 5 displays the radiation attenuation by lead shielding of Ga 68.

Ga 68 DOTATOC binds to somatostatin receptors, with highest affinity (K_i = 2.5± 0.5 nanomolar) for subtype 2 receptors (sstr2). Ga 68 DOTATOC binds to cells that express somatostatin receptors including malignant neuroendocrine cells, which overexpress sstr2 receptors. Gallium 68 is a β+ emitting radionuclide with associated 511 keV annihilation photons that allow positron emission tomography (PET) imaging.

The relationship between Ga 68 DOTATOC plasma concentrations and successful imaging was not explored in clinical trials.

Study A (NCT: 01619865) included 220 subjects with known or suspected SSTR positive tumors referred for diagnosis or evaluation of disease extension before or after treatment. A total of 178 of the 220 patients (81%) had a history of neoplasm at the time of Ga-68 DOTATOC imaging. In 177 of the 220 patients, sufficient data to establish NET status per composite reference was available for efficacy evaluation. Table 6 shows the performance of Ga-68 DOTATOC in the detection of NETs for Study A.

Study B (NCT: 01869725) included 62 patients with histologically positive NET or other SSTR positive tumor referred for evaluation of disease before or after treatment. In 59 of the 62 patients, sufficient data to establish NET status per composite reference was available for efficacy evaluation. The estimated positive and negative percent agreements were 92% and 75% for reader 1 and 90% and 75% for reader 2, respectively.

Store Ga 68 DOTATOC Injection upright in a lead shielded container at 25°C (77°F); excursions permitted to 15°C to 30°C (59°F to 86°F).

Receipt, transfer, handling, possession or use of this product is subject to the radioactive material regulations and licensing requirements of the U.S. Nuclear Regulatory Commission, Agreement States or Licensing States as appropriate. Store and dispose of Ga 68 DOTATOC Injection in accordance with the regulations and a general license, or its equivalent, of an Agreement State or a Licensing State.

Radiation Risk

Advise patients to drink water to ensure adequate hydration prior to their PET study and recommend they drink and urinate as often as possible during the first hours following the administration of Ga 68 DOTATOC Injection, in order to reduce radiation exposure [see Dosage and Administration (2.3) and Warnings and Precautions (5.1)].

Lactation

Advise a lactating woman to interrupt breastfeeding and pump and discard breast milk for 8 hours after Ga 68 DOTATOC Injection administration in order to minimize radiation exposure to a breastfed infant [see Use in Specific Populations (8.2)].